3-DIMENSIONAL NMR MICROSCOPIC IMAGING OF COAL SWELLING IN PYRIDINE

Results from two different NMRI techniques for spatially mapping the mobile proton distribution in coals swollen with pyridine-d5 or pyridine are reported. Three-dimensional (3-D) back-projection methods using a reconstruction algorithm based on a Radon transform inversion were employed to image a specimen of Utah Blind Canyon coal swollen with pyridine-d5. Images of the mobile macromolecular structure of Utah coal resulting from solvent swelling were obtained using T1 contrasting. Solvent penetration was also monitored using T2 weighting in a 3-D gradient-recalled echo pulse sequence and image reconstruction by 3-D Fourier transform methods. Using this technique, images of Utah Blind Canyon and West Virginia Lewiston-Stockton coals swollen with pyridine were obtained which show the distribution of the ingressed solvent. The presence of macerals, microfractures, and mineral regions which differ with regard to pyridine accessibility were contrasted in the images with a resolution of 40-80 mum over three spatial dimensions.